EXPRESSION PROFILING OF TRANSCRIPTION FACTORS UNDER DROUGHT STRESS AT SEEDLING STAGE IN BREAD WHEAT (TRITICUMAESTIVUM L.)

This study sheds light on the regulatory mechanisms underlying drought stress tolerance at early development stages in bread wheat (Triticum aestivum L.). Two bread wheat cultivars with contrasting genotypes, namely Giza 168 as the high-yielding tolerant cultivar and Gemmiza 10 as the sensitive cultivar, were utilized in this study. RNA-Seq data were subjected to hierarchical clustering analysis and resulted in the occurrence of six differentially expressed (DE) patterns for each cultivar. Nine TFs were consistently regulated in the two cultivars of which three corresponding to bZIP protein isoform 1, ethylene-responsive (ER) erf053-like, and heat stress a-3-like were upregulated at 12 h time point, while three other TFs corresponding to asg4-like (two hits) and ER rap2-2-like were downregulated. The last three TFs corresponding to ER1-like isoform x3 and WRKY40-like (two hits) were downregulated at 2 and 12 h time points. There are three other TFs that are highly expressed in the drought-tolerant cultivar. Two of these TFs (e.g., bHLH49-like and bHLH135-like) were upregulated at 2 h time point, while the third (e.g., MYB39-like) was upregulated at 12 h time point. We speculate that sensitivity to drought stress in GM10 might be due to the absence of regulation of some bHLH, MYB and NAC transcription factors, besides the downregulation of three members of WRKY family, namely WRKY1-like (two hits), WRKY18-like and WRKY40-like (four hits). Further expression profiling influencing the differentially expressed TFs along with their concordantly expressed stress-related TFs are required to be studied further. Regulatory mechanisms for drought stress tolerance in this study can be utilized further in improving crop productivity under adverse conditions via metabolic engineering approaches.